PROJECT SUMMARY The destructive effects of early adversity, such as chronic poverty and child maltreatment, substantially increase the risk for mental and physical health disorders across the lifespan. Understanding theoretically- informed mechanisms through which child adversity eventuates in psychopathology and poor physical health as well as the processes that may ameliorate those toxic effects, are top public health priorities. There is a significant gap regarding prospective, longitudinal research that delineates how adversity ?gets under the skin?, as well as processes that may protect children from early adversity. Informed by the Ecological-Transactional Model of Child Maltreatment and the Biological Embedding of Child Adversity Model, the current project aims to 1) prospectively examine the potentiating effect of early adversity on children's psychological and physical health; (2) understand mechanisms linking adversity to child health, with a focus on parent regulatory processes (psychopathology, cortisol), and children's behavioral (EF, emotion regulation, effortful control, lability), and biological regulation (cortisol, inflammation); and (3) evaluate the role of caregiving support on child health outcomes as a function of a parenting intervention that increased maternal support. To accomplish these aims, we will assess mother-child dyads (N = 240) who previously participated in a longitudinal randomized clinical trial (RCT) of a parenting intervention for maltreated preschool-aged children and their mothers, Reminiscing and Emotion Training (RET). Maltreating families were randomized into the RET condition or a Community Standard (CS) case management condition. A comparison condition of demographically matched nonmaltreating families (NC) was also included. All children had experienced significant adversity between ages 3-6, when enrolled. In the current proposal, 240 families will participate in two new follow-up assessments, one year apart, when children are ages 8-11. The multi-method, multi- domain battery includes assessment of adversity and child maltreatment, child behavioral and biological self- regulation, maternal regulation, maternal and alternate caregiver support, and child psychological (internalizing, externalizing) and physical health (metabolic risk). Preliminary evidence indicates that the RET intervention improved maternal support; thus, our design provides a unique opportunity to experimentally evaluate the protective role of caregiving support on children's self-regulation and physiology, and whether relational interventions may improve physical as well as mental health. Overall, the results may have significant implications for intervention science, public health, and social policies designed to reduce the burden of mental and physical health problems among children exposed to early adversity. Moreover, it will advance our theoretical model by delineating specific mechanisms associated with the cascading influence of early life adversity and maltreatment on child behavioral and physical health outcomes, as well as establishing a key modifiable process that may ameliorate negative effects via the RET intervention.